1. Field
The presently disclosed subject matter relates to a vehicle headlight, and more particularly to a small vehicle headlight using a semiconductor light source and a movable mirror, which can provide various light distribution patterns from at least one small light-emitting opening for a low beam, a high beam and the like, and which can vary a favorable light distribution pattern in accordance with surroundings such as an oncoming vehicle, a forward travelling vehicle, a road, etc.
2. Description of the Related Art
Vehicle headlights using a semiconductor light source and a movable mirror, which can vary a light distribution pattern to maintain a high visibility in accordance with surroundings such as an existence of an oncoming vehicle, a forward travelling vehicle and the like have been developed in recent years. Such a conventional vehicle headlight using a semiconductor light source and a movable mirror is disclosed in Patent Document No. 1 (Japanese Patent No. 4,881,255). FIG. 5 is a schematic side cross-sectional view showing this conventional vehicle headlight.
The conventional vehicle headlight 200 includes: a housing 202 having an opening; an outer lens 203 located adjacent the housing 202 so as to cover the opening; a turning board 204 located in the housing 202; a movable mirror 209 located on the turning board 204 in a direction toward the outer lens 203; an actuator 207 rotating the movable mirror 209 via the turning board 204; a base 208 supporting the turning board 204; a terminal 210 located on the base 208; a bracket 205 attaching the terminal 210 located on the base 208 to the housing 202; a semiconductor light source 201 emitting a visual light toward the movable mirror 209; and a controller 206 controlling the actuator 207 and the semiconductor light source 201 while associating the visual light emitted from the semiconductor light source 201 with the movable mirror 209 via the turning board 204 and the actuator 207.
The controller 206 includes: a central processing unit (CPU) 211; a memory 212 storing a program for operating the CPU 211, data received by the CPU 211, data outputted from the CPU 211 and the like; a light source controller 213 driving the semiconductor light source 201; and an actuator controller 214 operating the actuator 207 to rotate the movable mirror 209 along with the turning board 204 while associating the visual light emitted from the semiconductor light source 201 with the movable mirror 209 via the turning board 204 and the actuator 207.
According to the conventional vehicle headlight 200, the vehicle headlight 200 may form predetermined light distribution patterns by emitting the visual light toward the movable mirror 209 from the semiconductor light source 201 and by reflecting the visual light with the movable mirror 209 while rotating the turning board 204 so that the movable mirror 209 scans the visual light in a horizontal direction. In this case, the vehicle headlight 200 may further include another actuator, which rotates the turning board 204 in a vertical direction so that the movable mirror 209 can adjust the visual light in the vertical direction.
However, the above-described structure of the headlight 200 need to locate the semiconductor light source 201 at least either one of the vertical direction with respect to the movable mirror 209 or the horizontal direction with respect to the movable mirror 209. The conventional vehicle headlight 200 using such a structure may be subject to a large-scaled headlight, and therefore may be difficult to employ as a headlight for a small size car such as a single passenger vehicle, etc.
In addition, when the actuator 207, which continuously scans at high speed using a forward reverse control method, fails to operate properly due to any cause such as a disconnection, a mechanical fatigue and the like, the movable mirror 209 should return at a default position by an original function of a torsion bar 204a connecting between the actuator 207 and the turning board 204 as shown in FIG. 5. In this case, the conventional vehicle headlight 200 may emit the visual light intensively in a constant direction by the movable mirror 209, which stays at the default position, and therefore may not only cause harassments for pedestrians and oncoming vehicles but also may risk to a driver safety.
A scanning image display device using the above-described similar structure is disclosed in Patent Document No. 2 (International Publication WO2009/133698), and also an image projecting device using the above-described similar structure is disclosed in Patent Document No. 3 (International Publication WO2010/021215). These conventional devices may project image data along with visual lights while preventing a twist in the image data. However, light source devices disclosed in these conventional devices may also cause problems similar to these of the conventional headlight 200 as described above.
The above-referenced patent Documents and additional patent Documents are listed below and are hereby incorporated with their English specifications and abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent No. 4,881,255    2. Patent Document No. 2: International Publication WO2009/133698    3. Patent Document No. 3: International Publication WO2010/021215    4. Patent Document No. 4: Japanese Patent Application Laid Open JP2009-223165    5. Patent Document No. 5: Japanese Patent No. 4,092,283